This invention relates to a roll forming machine for producing a rain gutter and, more particularly, to a shear assembly disposed in a cutting station at the exit end of the roll forming machine.
Roll forming machines for producing rain gutters are generally well known. In such a machine, the gutters are formed from a supply coil of sheet metal which is finished on a first side so that the exterior of the finished gutter has an aesthetically pleasing appearance. As the sheet metal is driven through the machine along a predetermined path of travel, its lateral profile is gradually transformed from a flat sheet into a downwardly concave trough having a desired lateral profile and with the finished side of the sheet metal forming the exterior surface of the trough. As the finished gutter exits the machine, it passes through a cutting station including a shear assembly which may be selectively activated to sever the gutter so that a desired length of finished gutter is separated from the partially finished gutter which remains in the machine. Activation of the shear assembly is typically by means of a manually operated lever which drives a cutting blade between a pair of spaced die plates and through the finished gutter. Due to the shape of the gutter being a downwardly concave trough, to achieve a neatly finished cut, it would be desirable to have the blade driven both downwardly and laterally. This requires a split blade, wherein during a phase of the blade movement, the two blade parts are separated to achieve the outwardly lateral cutting action. However, during this phase of the cutting operation, a bent portion of the gutter profile is typically deformed so that the blade is forced to cut through multiple thicknesses of the gutter material. It would therefore be desirable to provide a mechanism whereby the lateral movement of the two blade parts is achieved with maximum mechanical advantage so that a neat cut is achieved without jamming.